So you are getting new cabinets, countertops or even new tile installed. Who do you want to have disconnecting and reconnecting your plumbing. Surely not the cabinet installer? What about the countertop person? Of course not! You need to have a licensed and insured professional plumber!
Most people think it's easy to disconnect their own plumbing. In other cases, the cabinet company may say "it is not a big deal". I've received a few too many calls to go and fix a pipe or valve that broke while someone was disconnecting or reconnecting the plumbing. Of course this ends up costing the client more than if they had called us in the first place!
Let's say you are installing new countertops. The countertop person reconnects the faucet and leaves. You go out for the day and return to a flood because he didn't tighten the fitting well enough or he over-tightened it and it blew, or he forgot to reconnect the dishwasher, or he had to replumb under the sink because the configuration was different and he failed to glue the fittings together. What happens next is that you get upset, take out your mop and clean up the mess. In a tizzy, you call the countertop company and they explain that they are not licensed plumbers. Then you have to call a plumber! You may be wondering why they didn't they tell you that when you ordered the countertop or cabinet? Plus, their insurance will not cover it and your homeowners insurance probably will not cover it either since the person who installed it was not a licensed & insured professional. This means that you may have to pay for the entire damage out of pocket. That may add up to a lot of money! Then you will have to check for damage to the cabinets, flooring and furniture, apart from suffering the stress of the event.
Let's take another scenario. You live in a condo and someone lives below you. You have new tile installed and the tile guys pull the existing toilet, they finish the job and reinstall your toilet. Except they forget to install a wax ring. Guess what happens every time you flush that toilet! Water seeps through the floor, and into the ceiling of the people below. Now you have the expense of having your floor checked for mold because this happens over time and may not show up right away, as well as the expense of your neighbors ceiling repair!
The moral of the story is that you should always hire a licensed and insured plumber for you disconnects and reconnects. In the long run it will save you money and you know that the job is done correctly.